Waste liquid switching valve

Abstract

To provide a waste liquid selector valve which enables fluid to flow more easily.SOLUTION: A waste liquid selector valve 11 includes: a valve body 13 in which a main passage 15 extending linearly along a main passage axis L is formed; and multiple valve mechanism parts 17 provided on the main passage 15. Each valve mechanism part 17 includes: a valve chamber 21 provided on the main passage 15; and a valve body 23 which is disposed in the valve chamber and has a taper part 23b at a tip. The valve body 13 is formed with: a branch passage 27 extending in a direction of a branch passage axis M perpendicular to the main passage axis L; and a contraction part 41 which extends between the valve chamber 21 and the branch passage 27 and has a smooth inner peripheral surface which narrows from the valve chamber 21 to the branch passage 27. The valve body 23 is reciprocated in a direction of the branch passage axis M to move an outer peripheral surface of the taper part 23b of the valve body 23 close to or away from the inner peripheral surface of the contraction part 41 and thereby open or close the valve mechanism part 17.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a waste liquid switching valve used in piping lines in various industrial fields such as chemical factories, semiconductor manufacturing, food, and bio, which can switch waste liquid lines to discharge fluids.

Background Art

[0002] In the cleaning process of semiconductor manufacturing, after a plurality of liquids such as chemicals and pure water are switched and supplied to a cleaning tank, they are discharged from the tank of the cleaning tank through a discharge line. From the perspective of waste liquid treatment, it is preferable that the used liquids are collected by switching the discharge line for each type. For this purpose, it is conceivable to use a switching valve in the discharge line. For example, as the switching valve, a flow path switching device as disclosed in Patent Document 1 or Patent Document 2 can be used. In addition, in the semiconductor cleaning process, in addition to a batch-type cleaning device that simultaneously cleans a large number of wafers in one cleaning tank, in order to be able to use a cleaning liquid suitable for the material used for each wafer in response to a small quantity and a variety of products, a single wafer type cleaning device that cleans each wafer in one cleaning tank has also been increasingly adopted.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In single-wafer washing systems, washing tanks are arranged in multiple stages to allow for parallel processing in order to increase throughput. Furthermore, wastewater from the washing tanks of the washing system is typically discharged using the difference in head pressure across the wastewater lines. Therefore, if the system is multi-staged while keeping the overall size of the system manageable, the head pressure difference between each washing tank and the switching valve becomes smaller. However, conventional flow path switching devices have high pressure loss and a small so-called volume coefficient Cv, resulting in a low wastewater discharge flow rate. This leads to a problem where the wastewater tanks of the washing tanks are prone to overflow.

[0005] Therefore, the object of the present invention is to solve the problems of the prior art and provide a waste liquid switching valve that facilitates fluid flow. [Means for solving the problem]

[0006] In view of the above objectives, the present invention provides a waste liquid switching valve comprising a valve body having a main flow path formed inside that extends linearly along the axis of the main flow path, and a plurality of valve mechanisms provided on the main flow path, wherein each valve mechanism comprises a valve chamber provided on the main flow path and a valve body disposed within the valve chamber and having a tapered portion at its tip, the valve body has a branch flow path extending in the direction of a branch flow path axis perpendicular to the axis of the main flow path, and a throttling portion extending between the valve chamber and the branch flow path and having a smooth inner surface that narrows from the valve chamber toward the branch flow path, and the valve mechanism is opened and closed by reciprocating the valve body in the direction of the axis of the branch flow path to bring the outer surface of the tapered portion of the valve body into contact with and away from the inner surface of the throttling portion. Furthermore, the valve chamber is formed to extend beyond the main flow path in the direction of the width axis perpendicular to the main flow path axis and the branch flow path axis, and the length of the cross-section of the main flow path in the direction of the width axis is greater than the length of the cross-section of the branch flow path axis. A waste liquid switching valve is provided.

[0007] In the above-described wastewater switching valve, the valve mechanism is opened and closed by bringing the outer surface of the tapered tip of the valve body into contact with and separating from the smooth inner surface of a throttling section, which is provided between the valve chamber and the branch passage so as to narrow from the valve chamber toward the branch passage. Here, "smooth" means that there are no protrusions or corners on the inner surface. If there is no throttling section and the tapered portion of the valve body is brought into contact with and separate from a corner formed at the boundary between the valve chamber and the branch passage, which extends in the direction of the branch passage axis perpendicular to the main passage axis, the flow area between the tapered portion and the corner of the valve body is rapidly narrowed and then rapidly expanded when the valve mechanism is open, resulting in a rapid change in fluid velocity and a large fluid pressure loss. In contrast, when the valve mechanism of the above-described wastewater switching valve is open, the fluid flows between the inner surface of the throttling section and the outer surface of the tapered portion of the valve body, and the flow area changes gradually, so the change in fluid velocity is also gradual and the pressure loss is small. Furthermore, since the tapered portion of the valve body moves in and out of contact with the smooth inner surface of the throttling portion, the fluid flow between the throttling portion and the tapered portion is not obstructed by protrusions or the like. As a result, the pressure loss of the fluid from the valve chamber to the branch passage can be reduced, and the fluid flows more easily from the valve chamber to the branch passage. In addition, when the valve mechanism is in the closed state, the outer surface of the tapered portion of the valve body and the inner surface of the throttling portion come into contact within the throttling portion. Therefore, the volume of the valve body housed within the throttling portion increases, and the volume of the portion of the valve body protruding into the extension of the main passage within the valve chamber can be reduced. As a result, the valve body is suppressed from obstructing the fluid flow when the fluid flowing through the main passage passes through the valve mechanism in the closed state, making it easier for the fluid to flow through the waste liquid switching valve to the branch passage.

[0008] In the above-described waste liquid switching valve, it is preferable that the inner circumferential surface of the throttling portion is a smooth curved surface that curves in a convex shape.

[0009] Ma Before The cross-section of the main channel is rectangular in shape, with the length in the direction of the width axis being longer than the direction of the axis of the branch channel. but preferable.

[0010] Furthermore, it is preferable that the main flow path is connected to an external flow path via a connecting passage, the cross-section of the main flow path is larger than the cross-section of the connecting passage in the direction of the width axis, and it is even more preferable that the connecting passage includes an enlarged diameter portion which is tapered in the direction of the width axis toward the main flow path from the external flow path.

[0011] In the above-described waste liquid switching valve, the connection portion between the main flow path and the valve chamber may be chamfered.

[0012] Furthermore, in the waste liquid switching valve described above, the outer circumferential surface of the tapered portion of the valve body may include a front-side inclined surface located on the tip side and a rear-side inclined surface located further from the branch passage than the front-side inclined surface and having a larger angle with respect to the axis of the branch passage than the front-side inclined surface, such that the rear-side inclined surface is in contact with and away from the inner circumferential surface of the throttling portion.

[0013] In one embodiment, the main flow path extends between a first end and a second end connected to the connecting passage, and the plurality of valve chambers are provided at least at the first end and the second end. [Effects of the Invention]

[0014] According to the present invention, the pressure loss between the valve chamber and the branch channel can be reduced, making it easier for fluid to flow between the valve chamber and the branch channel. Furthermore, it is possible to suppress obstruction of fluid flow when the fluid flowing in the main channel passes through the valve mechanism when the valve is closed, making it easier for the fluid to flow from the waste liquid switching valve to the branch channel. Therefore, the fluid passes through the waste liquid switching valve more easily. As a result, even when a waste liquid switching valve is used in a waste liquid line with a small head difference, it is possible to suppress the decrease in flow rate and ensure a sufficient waste liquid flow rate. [Brief explanation of the drawing]

[0015] [Figure 1] This is a longitudinal cross-sectional view showing the overall configuration of the waste liquid switching valve according to the present invention. [Figure 2]It is a perspective view showing the state where the valve body of the waste liquid switching valve shown in FIG. 1 is cut. [Figure 3] It is a cross-sectional view of the valve body of the waste liquid switching valve shown in FIG. 1 when viewed from above FIG. 1. [Figure 4] It is a sectional view taken in the direction of the arrow of the valve body of the waste liquid switching valve along the line A-A in FIG. 3. [Figure 5] It is an enlarged cross-sectional view showing an enlarged valve chamber portion of the valve body in a modified form of the waste liquid switching valve according to the present invention.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the waste liquid switching valve according to the present invention will be described with reference to the drawings. First, referring to FIG. 1, the overall configuration of the waste liquid switching valve 11 will be described.

[0017] 3] The waste liquid switching valve 11 includes a valve body 13 in which a main flow path 15 extending linearly along the main flow path axis L is formed inside, and a plurality of valve mechanism portions 17 provided on the main flow path 15. One end of the main flow path 15 in the direction of the main flow path axis L is connected to an external flow path via a connection path 19. In the illustrated embodiment, the waste liquid switching valve 11 includes three valve mechanism portions 17A, 17B, and 17C, but it may include two or four or more valve mechanism portions 17.

[0018] The valve mechanism portions 17A, 17B, and 17C have basically the same configuration. In the figure, the same reference numerals are given to the configurations common to each of the valve mechanism portions 17A, 17B, and 17C. However, in the following description, when referring to the configuration of a specific one of the valve mechanism portions 17A, 17B, and 17C, corresponding reference numerals are appended with the symbols A, B, and C, and when referring to the configuration common to each of the valve mechanism portions 17 rather than a specific valve mechanism portion 17A, 17B, or 17C, the symbols A, B, and C are not appended.

[0019] Each valve mechanism part 17 is composed of a valve chamber 21 provided on the main flow path 15, a valve body 23 disposed within the valve chamber 21, and a drive part 25 for driving the valve body 23. Each valve chamber 21 has a generally cylindrical inner peripheral surface and extends in the direction of the branch flow path axis M perpendicular to the main flow path axis L, and a plurality of valve chambers 21 are provided at equal intervals in the direction of the main flow path axis L. In the illustrated embodiment, a valve chamber 21C of the valve mechanism part 17C is provided at one end of the main flow path 15 connected to the connecting path 19 in the direction of the main flow path axis L, a valve chamber 21A of the valve mechanism part 17A is provided at the other end of the main flow path 15, and a valve chamber 21B of the valve mechanism part 17B is provided on the main flow path 15 between the valve chamber 21A and the valve chamber 21C.

[0020] A branch flow path 27 extending in the direction of the branch flow path axis M communicates with the valve chamber 21, and a valve seat is formed at the opening from the branch flow path 27 to the valve chamber 21. Further, the drive part 25 is attached to the valve body 13 so as to face the branch flow path 27 across the valve chamber 21 in the direction of the branch flow path axis M. By reciprocating the valve body 23 in the direction of the branch flow path axis M using the drive part 25 to bring the valve body 23 into contact with and away from the valve seat, the valve mechanism part 17 is opened and closed, and the flow and interruption between the main flow path 15 and the branch flow path 27 can be switched.

[0021] In the illustrated embodiment, the valve body 23 includes a diaphragm part 29 that extends radially outward from the outer peripheral part of the upper end of the valve body 23 and has a generally circular outer peripheral shape. The drive part 25 is composed of a drive part housing 31 in which a cylinder part serving as an accommodation space is formed inside, a piston 33 slidably accommodated in the cylinder part, a stem 35 that extends from the piston 33 toward the valve chamber 21 and is connected to the valve body 23, a diaphragm presser 37, and a biasing member 39 that biases the piston.

[0022] The valve body 13 has an opening that extends to each valve chamber 21 at a position opposite to the branch passage 27 in the direction of the branch passage axis M, and a diaphragm portion 29 is positioned to cover this opening. A diaphragm retainer 37 is attached to the bottom of the drive unit housing 31 to cover the opening of the cylinder portion. The outer edge of the diaphragm portion 29 is sandwiched between the diaphragm retainer 37 and the valve body 13 by the drive unit housing 31, which is fixed to the valve body 13 with bolts or the like. In this way, the space between the valve chamber 21 and the drive unit 25 is partitioned by the diaphragm portion 29, and the valve body 23 is positioned inside the valve chamber 21 with the valve body 13 supported via the diaphragm portion 29. A stem 35 is connected to the valve body 23, which is supported by the diaphragm portion 29, and extends from the piston 33 through the diaphragm retainer 37.

[0023] The space within the cylinder is divided into two spaces by the piston 33. A biasing member 39 is positioned in one of these spaces, supplying and discharging drive fluid to the other space, thereby causing the piston 33 to reciprocate in the direction of the branch flow path axis M, and moving the valve body 23 toward and toward the valve seat via the stem 35. More specifically, in the valve mechanism 17A, a biasing member 39A is positioned in the space below the piston 33A within the cylinder in Figure 1, so as to apply a biasing force that moves the piston 33A away from the valve chamber 21A. Therefore, by supplying drive fluid to the space above the piston 33A within the cylinder, the piston 33A is moved toward the valve chamber 21A in the direction of the branch flow path axis M against the biasing force of the biasing member 39A, and the valve body 23 is moved toward the valve seat via the stem 35A from a state away from the valve seat in the direction of the branch flow path axis M, and brought into contact with the valve seat. Furthermore, by discharging the drive fluid from the space above the piston 33A in the cylinder, the biasing force of the biasing member 39A moves the piston 33A away from the valve chamber 21A in the direction of the branch flow path axis M, and moves the valve body 23 away from the valve seat via the stem 35A in the direction of the branch flow path axis M, thereby separating it from the valve seat.

[0024] On the other hand, in valve mechanism 17B and valve mechanism 17C, biasing members 39B and 39C are positioned in the space above the pistons 33B and 33C in the cylinder section so as to apply a biasing force to move the pistons 33B and 33C closer to the valve chambers 21B and 21C. Therefore, by supplying the drive fluid to the space below the pistons 33B and 33C in the cylinder section, the pistons 33B and 33C are moved away from the valve chambers 21B and 21C in the direction of the branch flow path axis M, against the biasing force of the biasing members 39B and 39C, and the valve body 23 is moved via the stem 35B and 35C in the direction of the branch flow path axis M, away from the valve seat, thereby separating it from the valve seat. Furthermore, by discharging the drive fluid from the space below the pistons 33B and 33C within the cylinder, the biasing force of the biasing members 39B and 39C moves the pistons 33B and 33C toward the valve chambers 21B and 21C in the direction of the branch flow path axis M, and moves the valve body 23 toward the valve seat via the stem 35A in the direction of the branch flow path axis M, thereby bringing it into contact with the valve seat.

[0025] In this way, by configuring the valve mechanism 17A and the valve mechanisms 17B and 17C to behave differently, even if the supply of driving fluid to the valve mechanisms 17A, 17B, and 17C is not performed, the valve mechanism 17A will open and the waste liquid will be discharged through the waste liquid switching valve 11.

[0026] As shown in Figure 1, the valve body 23 includes a cylindrical central portion 23a, a front tapered portion 23b that narrows from the central portion 23a towards the tip (the end closer to the branched passage 27), and a rear tapered portion 23c that narrows from the central portion 23a towards the drive portion 25, and has a generally spinning top shape. Preferably, the outer circumferential surface of the front tapered portion 23b includes a front inclined surface located towards the tip and a rear inclined surface located further from the branched passage 27 than the front inclined surface and extending at a larger angle with respect to the branched passage axis M than the front inclined surface. Also, as clearly shown in Figure 2, a generally funnel-shaped throttling portion 41 is provided between the valve chamber 21 and the branched passage 27, having a smooth cylindrical inner circumferential surface that narrows from the valve chamber 21 towards the branched passage 27. Preferably, the inner circumferential surface of the throttling portion 41 is a smooth curved surface that curves in a convex shape, but it may also be a planar inclined surface. In this specification, "smooth" means that there are no protrusions or corners on the inner circumferential surface. In the valve mechanism 17, the tapered outer surface of the front tapered portion 23b of the valve body 23 moves toward and away from the smooth inner circumferential surface of the throttling portion 41, which has such a configuration, thereby opening and closing the valve chamber 21 and the branch passage 27. In other words, the inner circumferential surface of the throttling portion 41 functions as a valve seat.

[0027] In conventional switching valves, where the branch passage 27 opens directly to the valve chamber 21, a roughly right-angle corner is formed at the connection point between the inner surface of the branch passage 27 and the wall surface of the valve chamber 21. This corner functions as a valve seat, causing the outer surface of the front tapered portion 23b of the valve body 23 to move toward and away from the corner. When the front tapered portion 23b of the valve body 23 separates from the corner and the valve opens, the flow area between the front tapered portion 23b of the valve body 23 and the corner is rapidly narrowed and then rapidly expanded, causing a rapid change in the fluid velocity flowing from the valve chamber 21 to the branch passage 27. As a result, the fluid pressure loss increases, making it easier for the flow rate from the valve chamber 21 to the branch passage 27 to decrease. In contrast, in the waste liquid switching valve 11, when the valve mechanism 17 is in the open state and the outer surface of the front tapered portion 23b of the valve body 23 is separated from the inner surface of the throttling portion 41, the flow path area between the outer surface of the front tapered portion 23b of the valve body 23 and the inner surface of the throttling portion 41 changes relatively slowly, so the change in fluid velocity also becomes relatively slow. As a result, the fluid pressure loss is also reduced, making it easier for the fluid to flow from the valve chamber 21 to the branch flow path 27, and making it possible to suppress the decrease in flow rate from the valve chamber 21 to the branch flow path 27 due to pressure loss.

[0028] Furthermore, in the waste liquid switching valve 11, the inner circumferential surface of the throttling portion 41 is smooth, and no protrusions or the like are provided on the inner circumferential surface, so that the outer circumferential surface of the front tapered portion 23b of the valve body 23 directly contacts the inner circumferential surface of the throttling portion 41. Therefore, the change in flow velocity when the fluid flows between the outer circumferential surface of the front tapered portion 23b of the valve body 23 and the inner circumferential surface of the throttling portion 41 can be reduced, and the pressure loss is reduced, making it easier to further suppress the decrease in flow rate from the valve chamber 21 to the branch passage 27. In addition, if there are protrusions on the valve seat, slurry and the like may remain on the valve seat and mix with the cleaning agent that is then flushed, making it impossible to reuse the cleaning agent. In the waste liquid switching valve 11, since no protrusions are provided on the inner circumferential surface of the throttling portion 41, the residue of slurry and the like can be prevented. Furthermore, in the waste liquid switching valve 11 with the above-described configuration, when the valve mechanism 17 is in the closed state, the contact between the outer circumferential surface of the front tapered portion 23b of the valve body 23 and the valve seat (i.e., the inner circumferential surface of the throttling portion 41) occurs within the throttling portion 41. Therefore, compared to the case where the corner formed at the connection between the wall surface of the valve chamber 21 and the inner circumferential surface of the branch passage 27 becomes the valve seat, the volume of the portion of the valve body 23 that protrudes onto the extension of the main passage 15 within the valve chamber 21 can be reduced. As a result, when the fluid flowing through the main passage 15 passes through the valve mechanism (e.g., valve mechanism 17B or valve mechanism 17C) in the closed state and passes to the downstream side, the valve body 23 is suppressed from obstructing the flow of fluid, making it possible for the fluid to flow more easily downstream in the main passage 15. The fact that the valve body 23 includes a rear tapered portion 23c also contributes to the effect of reducing the volume of the portion of the valve body 23 that protrudes onto the extension of the main passage 15 within the valve chamber 21. Furthermore, from a similar viewpoint, the central portion 23a of the valve body 23 is the part with the largest diameter in the cross-section perpendicular to the branch flow path axis M, so it is preferable to reduce the thickness in the direction of the branch flow path axis M to the extent that the required strength can be maintained. The valve body 23 may also be constructed using only the front tapered portion 23b and the rear tapered portion 23c, without providing the central portion 23a.

[0029] When the outer circumferential surface of the front tapered portion 23b includes a front-side inclined surface and a rear-side inclined surface, it is preferable that the valve body 23 is configured such that the rear-side inclined surface moves toward and away from the inner circumferential surface of the throttling portion 41, as shown in the valve mechanism portion 17B and valve mechanism portion 17C in Figure 1. With this configuration, the fluid passing between the outer circumferential surface of the front tapered portion 23b of the valve body 23 and the inner circumferential surface of the throttling portion 41 is less likely to generate turbulence, fluid stagnation can be suppressed, and the adhesion of air bubbles to the valve body 23 can be suppressed.

[0030] Furthermore, if the inner circumferential surface of the throttling portion 41 is made of a smooth curved surface that curves in a convex shape, the outer circumferential surface of the front tapered portion 23b of the valve body 23 and the inner circumferential surface of the throttling portion 41 will be in line contact, reducing the contact area, which increases the sealing pressure and improves sealing performance.

[0031] Next, with reference to Figures 2 to 4, the structure of the waste liquid switching valve 11 will be further described.

[0032] As shown in Figure 2, the valve body 13 of the waste liquid switching valve 11 is provided with a connecting passage 19 to connect an external passage (not shown) and a main passage 15. The connecting passage 19 includes a straight pipe section 19a connected to the external passage and an enlarged diameter section 19b provided between the straight pipe section 19a and the main passage 15.

[0033] Furthermore, as can be clearly seen by referring to Figures 2 and 3, the valve chamber 21 has a diameter in a cross-section perpendicular to the branch passage axis M that is larger than the diameters of the connecting passage 19 and the branch passage 27, so that the valve body 23 can reciprocate inside in the direction of the branch passage axis M. For this reason, the valve chamber 21 is wider than the connecting passage 19 and the main passage 15 in the direction of the width axis N perpendicular to the main passage axis L and the branch passage axis M, and a part of the valve chamber 21 is convexly expanded in the direction of the width axis N relative to the connecting passage 19 and the main passage 15.

[0034] When using a waste liquid switching valve 11 in a single-wafer cleaning device equipped with multiple cleaning tanks, it is necessary to reduce the vertical width of the area occupied by the waste liquid switching valve 11, and the waste liquid switching valve 11 is positioned so that the branch flow path axis M is approximately horizontal. In detail, for example, the waste liquid switching valve 11 is positioned such that the drive unit 25 side of the waste liquid switching valve 11 is positioned slightly higher than the branch flow path 27 side. When the waste liquid switching valve 11 is used in such an arrangement, air bubbles contained in the fluid flowing in from the external flow path tend to be trapped and accumulate in the area particularly located above the portion of the valve chamber 21 that is convexly extended in the direction of the width axis N relative to the connecting passage 19 and the main flow path 15 (hereinafter simply referred to as the "extended portion 43"). Air bubbles accumulated in the extended portion 43 can hinder the smooth passage of the fluid flowing through the main flow path 15 downstream through the valve chamber 21 of the valve mechanism 17 when the valve is closed, and can be a cause of a decrease in waste liquid flow rate. In particular, if air bubbles accumulate in the expanded portion 43C of the valve chamber 21C of the valve mechanism 17C located on the side closer to the external flow path, it will have a significant impact on the reduction in flow rate.

[0035] To suppress the accumulation of air bubbles in the expanded portion 43, the waste liquid switching valve 11 reduces the amount of protrusion of the expanded portion 43 of the valve chamber 21 that protrudes in the direction of the width axis N relative to the main flow path 15 and the connecting passage 19, that is, it reduces the difference between the maximum dimensions of the main flow path 15 and the connecting passage 19 and the maximum dimensions of the valve chamber 21 in the direction of the width axis N. Specifically, the connecting passage 19 includes a straight pipe section 19a having a circular cross-section (a cross-section perpendicular to the main flow path axis L) and an enlarged diameter section 19b that tapers in the direction of the width axis N from the straight pipe section 19a connected to the external flow path toward the main flow path 15. In the illustrated embodiment, the enlarged diameter section 19b of the connecting passage 19 is connected to the valve chamber 21C of the valve mechanism section 17C provided at one end of the main flow path 15. In addition, the cross-section of the main flow path 15 is expanded in the direction of the width axis N, and the length of the cross-section of the main flow path 15 in the direction of the width axis N is greater than the length in the direction of the branch flow path axis M. In one embodiment, the cross-sectional shape of the main flow path 15 can be a roughly rectangular shape, as shown in Figure 4, where the length in the direction of the width axis N is greater than the length in the direction of the branch flow path axis M. However, the main flow path 15 may have other cross-sectional shapes as long as the amount of protrusion of the expanded portion 43 of the valve chamber 21 that protrudes from the main flow path 15 in the direction of the width axis N can be reduced. For example, it is possible to have an elliptical cross-section where the direction of the branch flow path axis M is the minor axis and the direction of the width axis N is the major axis. Furthermore, it is preferable that the cross-section of the main flow path 15 is larger than the cross-section of the enlarged diameter portion 19b of the connecting passage 19 in the direction of the width axis N.

[0036] Furthermore, as shown in Figure 2, in order to reduce the resistance of the fluid flowing through the main channel 15, it is preferable that the length of the main channel 15 (length of the maximum part in cross-section) and the length of the enlarged diameter portion 19b of the connecting channel 19 (length of the maximum part in cross-section) are equal to the length of the straight pipe portion 19a of the connecting channel 19 in the direction of the axis M of the branch channel, and it is even more preferable that the length of the valve chamber 21 is also equal to the length of the straight pipe portion 19a of the connecting channel 19.

[0037] As a variation of the waste liquid switching valve 11, as shown in Figure 5, a chamfered portion 45 may be provided by chamfering the connection between the inner surface of the main flow path 15 and the wall surface of the valve chamber 21 around the branch flow path axis M. The chamfered portion 45 may be configured with an R-chamfer to connect the inner surface of the main flow path 15 and the wall surface of the valve chamber 21 around the branch flow path axis M with a curved surface, or with a C-chamfer to connect the inner surface of the main flow path 15 and the wall surface of the valve chamber 21 around the branch flow path axis M with a flat surface. By providing such a chamfered portion 45, when the valve mechanism 17 is in the closed state, it becomes easier for the fluid to flow around the valve body 23, thus reducing the obstruction of the flow in the main flow path 15.

[0038] Next, we will explain the operation of the waste liquid switching valve 11 shown in Figure 1.

[0039] Fluid flows into the waste liquid switching valve 11 from an external flow path located in the external piping via a connecting passage 19. The fluid that flows into the waste liquid switching valve 11 circulates through the main flow path 15 via the connecting passage 19. Multiple valve mechanisms 17 provided in the main flow path 15 are selectively opened according to the type of waste liquid flowing in from the external flow path, and the valve mechanisms 17 that are not selected are closed. In the closed state of a valve mechanism 17, the drive unit 25 moves the valve body 23 toward the throttling portion 41 in the direction of the branch flow path axis M, and the outer circumferential surface of the front tapered portion 23b of the valve body 23 comes into contact with the inner circumferential surface of the throttling portion 41, preventing the inflow of fluid into the branch flow path 27. When the valve mechanism 17B and valve mechanism 17C are closed, the fluid in the main passage 15 flows into the valve chambers 21B and 21C, then bypasses the valve bodies 23B and 23C located in the valve chambers 21B and 21C, and flows to the main passage 15 downstream. In addition, in the waste liquid switching valve 11, the amount of protrusion of the expanded portion 43 of the valve chamber 21 relative to the main passage 15 and connecting passage 19 is small, so air bubbles that accumulate in the expanded portion 43 are easily discharged from the expanded portion 43 to the main passage 15 downstream by riding on the fluid flow, and the accumulation of air bubbles in the expanded portion 43 that obstructs the fluid flow in the main passage 15 is suppressed.

[0040] On the other hand, in the valve mechanism 17, which is selectively opened, the drive unit 25 moves the valve body 23 away from the throttling portion 41 in the direction of the branch flow path axis M, so that the outer circumferential surface of the front tapered portion 23b of the valve body 23 separates from the inner circumferential surface of the throttling portion 41, and the fluid is discharged from the valve chamber 21 to the branch flow path 27 by passing between the outer circumferential surface of the front tapered portion 23b of the valve body 23 and the inner circumferential surface of the throttling portion 41. Since the inner circumferential surface of the throttling portion 41 narrows in a funnel shape from the valve chamber 21 to the branch flow path 27, the change in flow path area is gradual and pressure loss is suppressed between the inclined outer circumferential surface of the front tapered portion 23b of the valve body 23 and the inner circumferential surface of the throttling portion 41, which has the effect of making it easier for fluid to flow from the valve chamber 21 to the branch flow path 27. Therefore, even when the head of the external flow path is small, it becomes easier to secure a sufficient waste liquid flow rate.

[0041] Although the waste liquid switching valve according to the present invention has been described above with reference to the illustrated embodiments, the present invention is not limited to the illustrated embodiments. For example, in the illustrated embodiments, three valve mechanisms 17 are provided, but two or four or more valve mechanisms 17 may be provided. Also, although the valve mechanisms 17 are provided at both ends of the main flow path 15 in the direction of the main flow path axis L, for example, the valve mechanism 17 on the connecting passage 19 side may be provided closer to the center in the direction of the main flow path axis L, so that the connecting passage 19 is directly connected to the end of the main flow path 15. Furthermore, as the drive unit 25, a forward-acting type, a reverse-acting type, and a double-acting type may be appropriately selected and used depending on the purpose. [Explanation of Symbols]

[0042] 11. Waste liquid switching valve 13 Valve body 15 Main channel 17, 17A, 17B, 17C Valve mechanism 19 connecting routes 19a Straight pipe section 19b Expanded diameter part 21,21A,21B,21C Valve chamber 23, 23A, 23B, 23C valve bodies 23a Front tapered section 27, 27A, 27B, 27C Branch channel 41 Aperture section 43 Expansion section 45 Chamfered section

Claims

1. A waste liquid switching valve comprising a valve body having a main flow path formed inside that extends linearly along the axis of the main flow path, and a plurality of valve mechanisms provided on the main flow path, Each valve mechanism comprises a valve chamber provided on the main flow path and a valve body disposed within the valve chamber and having a tapered portion at its tip. The valve body has a branch flow path extending in the direction of a branch flow path axis perpendicular to the main flow path axis and a throttling portion extending between the valve chamber and the branch flow path and having a smooth cylindrical inner surface that narrows from the valve chamber toward the branch flow path. The valve mechanism is opened and closed by reciprocating the valve body in the direction of the branch flow path axis, causing the outer surface of the tapered portion of the valve body to move toward and away from the inner surface of the throttling portion. The valve chamber is formed to extend beyond the main flow path in the direction of a width axis perpendicular to the main flow path axis and the branch flow path axis, and the length of the cross-section of the main flow path in the direction of the width axis is greater than the length of the cross-section of the branch flow path axis.

2. The waste liquid switching valve according to claim 1, wherein the inner circumferential surface of the throttling portion is a smooth curved surface that curves in a convex shape.

3. The waste liquid switching valve according to claim 1, wherein the cross-section of the main flow path has a rectangular shape that is longer in the direction of the width axis than in the direction of the axis of the branch flow path.

4. The waste liquid switching valve according to claim 1 or claim 3, wherein the main flow path is connected to an external flow path via a connecting passage, and the cross-section of the main flow path is larger than the cross-section of the connecting passage in the direction of the width axis.

5. The waste liquid switching valve according to claim 4, wherein the connecting passage includes an enlarged diameter portion that is tapered in the direction of the width axis toward the main passage from the external passage.

6. A waste liquid switching valve according to any one of claims 1 to 5, wherein the connection portion between the main flow path and the valve chamber is chamfered.

7. A waste liquid switching valve according to any one of claims 1 to 6, wherein the outer circumferential surface of the tapered portion of the valve body includes a front inclined surface located on the tip side and a rear inclined surface located further from the branch passage than the front inclined surface and extending at a larger angle than the front inclined surface with respect to the axis of the branch passage, and the rear inclined surface moves toward and away from the inner circumferential surface of the throttling portion.

8. The waste liquid switching valve according to claim 4 or 5, wherein the main flow path extends between a first end and a second end connected to the connecting passage, and the plurality of valve chambers are provided at least at the first end and the second end.

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